Previously the medical device industry has produced a wide variety of electronic and mechanical devices for treating patient medical conditions. Depending upon medical condition, medical devices can be surgically implanted or connected externally to the patient receiving treatment. Clinicians use medical devices alone or in combination with therapeutic substance therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best, and sometimes the only, therapy to restore an individual to a more healthful condition and a fuller life. One type of medical device is an implantable infusion device.
An implantable therapeutic substance infusion device is implanted by a clinician into a patient at a location appropriate for the therapy. Typically, a therapeutic substance infusion catheter is connected to the device outlet and implanted to infuse the therapeutic substance such as a drug or infusate at a programmed infusion rate and predetermined location to treat a condition such as pain, spasticity, cancer, and other medical conditions. Many therapeutic substance infusion devices are configured so the device can be refilled with therapeutic substance through a septum while the device is implanted. Then the time the device can be implanted may not be limited by therapeutic substance stored capacity of the device. An example of an implantable therapeutic substance infusion device is shown in Medtronic, Inc. product brochure entitled “SynchroMed® Infusion System” (1995).
The therapeutic substance infused into a patient is stored in the pump in a sealed reservoir. The substance in the reservoir flows from the reservoir via internal fluid handling components to the motor and pump components where it is metered and then flows to the pump output.
In a peristaltic pump the substance flows through a compressible tube, one of several fluid handling components, and this tube is slightly permeable to water, and possibly some compounds and ions. Water vapor and other materials that may diffuse through the tube walls and become trapped inside the pump may be corrosive to mechanical or electrical components inside the pump. In particular, electrical components such are electronic circuits and motors are particularly vulnerable to damage and loss of function due to certain types of contamination.
Electrically powered implanted infusion devices consume energy delivered typically by a battery, also called a power source. Wires and connections inside the pump carry electrical energy from the power source to the motor. These wires and connections must be designed to be isolated from corrosive materials or made impervious to corrosion by corrosive materials. If this corrosion immunity is not accomplished, the pump will likely need to be replaced due to malfunction prior to the end of its normal service life. Replacement usually requires a costly, inconvenient and potentially problematic surgery for the patient and attending physician. For these reasons there is a need for a pump with various components of the motor coil connector and sealing system inside the pump that are carefully designed to eliminate or minimize potentially detrimental corrosive effects from corrosive materials.